Grilling appliance with automated platen leveling and gap calibration system

ABSTRACT

A method of calibrating a grill is provided including performing a first calibration run. A first calibration run includes monitoring a current of a leveling mechanism as the first grilling surface moves into contact with a second opposite grilling surface to determine a first location of the grilling surface. The current of the leveling mechanism is also monitored as the first grilling surface moves out of contact with the second grilling surface to determine a second location of the first grilling surface. A first calibration setting including the first location and the second location is stored in the control.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional patentapplication Ser. No. 61/908,809 filed Nov. 26, 2013, the entire contentsof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to a grill, and moreparticularly to a grill that automatically calibrates a gap between anupper grilling surface and a lower grilling surface.

Grills or griddles are used to cook various foods, such as hamburgersfor example. In some conventional grills, the sides of the food aregrilled sequentially. The food is placed on a grilling surface, thusgrilling the side of the food that contacts the grilling surface. Afterthat side of the food is cooked, the food is manually flipped to cookthe opposite side. After both sides of the food are cooked, the food ismanually removed from the grill for serving.

In other conventional grills, both sides of the good are grilledsimultaneously. After manually programming the type of food into acontrol unit, the food is placed on a lower grilling surface. An upperplaten assembly having an upper grilling surface is then lowered on thefood, positioning the food in a gap between the upper and lower grillingsurfaces to simultaneously grill both sides of the food. After apredetermined amount of time has passed, the upper platen assemblyraises and the food is manually removed from the grill.

To ensure optimal performance, the upper grilling surface should belevel to ensure that the upper grilling surface uniformly contacts thefood. If the upper platen assembly is not level, a service technicianmust travel to the site to manually calibrate the grill. This requiresadditional cost and labor. Hence, there is a need in the art for a grillthat automatically calibrates a gap between an upper grilling surfaceand a lower grilling surface and that overcomes the drawbacks of theprior art.

BRIEF DESCRIPTION OF THE INVENTION

According to an aspect of the invention, a method of calibrating a grillis provided including performing a first calibration run. A firstcalibration run includes monitoring a current of a leveling mechanism asthe first grilling surface moves into contact with a second oppositegrilling surface to determine a first location of the grilling surface.The current of the leveling mechanism is also monitored as the firstgrilling surface moves out of contact with the second grilling surfaceto determine a second location of the first grilling surface. A firstcalibration setting including the first location and the second locationis stored in the control.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 schematically illustrates a perspective view of a grill in alowered position according to an embodiment of the invention;

FIG. 2 schematically illustrates a perspective view of a grill in araised position according to an embodiment of the invention;

FIG. 3 schematically illustrates a perspective view of a grill in alowered position with the shell removed according to an embodiment ofthe invention;

FIG. 4 schematically illustrates a top view of the grill with the shellremoved;

FIG. 5 schematically illustrates a perspective view of disc and a cableof a motor according to an embodiment of the invention;

FIG. 6 schematically illustrates a side view of the motor when rotatingthe disc in a first direction according to an embodiment of theinvention;

FIG. 7 schematically illustrates a side view of the motor when rotatingthe disc in a second direction according to an embodiment of theinvention;

FIG. 8 schematically illustrates a cross-sectional view of a grillaccording to an embodiment of the invention; and

FIG. 9 schematically illustrates a method of calibrating a firstgrilling surface of the grill according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, a grill 20 is illustrated in a lowerposition and a raised position, respectively. The grill 20 includes alower platen assembly 22 and an upper platen assembly 24 movablyattached to the lower platen assembly 22 by a mounting structure 28,such as a hinge for example. A handle 26 on the upper platen assembly 24can be grabbed by an operator to move the upper platen assembly 24relative to the lower platen assembly 22 between the lowered positionand the raised position. The lower platen assembly 22 and the upperplaten assembly 24 each include a respective grilling surface 30 and 32.When the upper platen assembly 24 is lifted by an operator to the raisedposition, the lower grilling surface 30 is exposed.

Food items 34 are placed on the lower grilling surface 30 by theoperator for cooking. In one example, the food items 34 are hamburgers.The upper platen assembly 24 may be moved downwardly to the loweredposition, either automatically or by an operator applying a force to thehandle 26, positioning the food item 34 in a gap 36 between the lowergrilling surface 30 and the upper grilling surface 32. An arm 42contacts the lower grilling surface 30 to provide a mechanical stop thatdefines the gap 36 between the upper grilling surface 32 and the lowergrilling surface 30. The grilling surfaces 30 and 32 are heated by aheater (not shown) to cook the food items 34.

As shown in FIGS. 3 and 4, the upper platen assembly 24 includes aplurality of leveling mechanisms 38, such as a three leveling mechanisms38 a, 38 b, 38 c tier example, configured to automatically level theupper grilling surface 32 relative to the lower grilling surface 30. Inthe illustrated, non-limiting embodiment, each leveling mechanism 38 a,38 b, 38 c is arranged within a shell 44 (see FIGS. 1 and 2) andincludes a motor 46 a, 46 b, 46 c and a disc 52 a, 52 b, 52 c operablycoupled to the shaft 48 a, 48 b, 48 c of the motor 46 a, 46 b, 46 c. Acontrol 78 independently controls the motor 46 a, 46 b, 46 c of eachleveling mechanism 38 a, 38 b, 38 c. The upper grilling surface 32 issuspended from a plurality of cables 58 a, 58 b, 58 c arranged within agroove 54 a, 54 b, 54 c of each rotatable disc 52 a, 52 b, 52 c. A firstend 60 a, 60 b, 60 c of each cable 58 a, 58 b, 58 c is attached to anupper surface 88 of the upper grilling surface 32 by an attachmentmember 62 a, 62 b, 62 c. An opposing second end 64 a, 64 b, 64 c of eachcable 58 a, 58 b, 58 c is attached in the groove 54 a, 54 b, 54 c of adisc 52 a, 52 b, 52 c of one of the plurality of leveling mechanisms 38a, 38 b, 38 c (FIG. 5). Although cables 58 a, 58 b, 58 c are illustratedand described, other tension members, such as metal drive belts forexample, are within the scope of the invention. In addition, althoughthree leveling mechanisms 38 a, 38 b, 38 c are illustrated and describedherein, it is understood that any number of leveling mechanisms 38 canbe used.

Returning to FIG. 4, a first cable 58 a of the first leveling mechanism38 a may be attached near a first corner 66 of the upper surface 88 withthe attachment member 62 a, and a second cable 58 b of the secondleveling mechanism 38 b may be attached near a second corner 68 of theupper surface 88 with the attachment member 62 b. An edge 70 is locatedbetween the first corner 66 and the second corner 68. The third cable 58c may be attached to the upper surface 88 with the attachment member 62c at a location between a third corner 72 and a fourth corner 74 of theupper grilling surface 32. In one example, the attachment member 62 c issubstantially centrally between the third corner 72 and the fourthcorner 74. An edge 76 opposite to the edge 70 is located between thethird corner 72 and the fourth corner 74. Therefore, the cables 58 a, 58b and 58 c are attached to the upper surface 88 of the upper grillingsurface 32 in a substantially triangular pattern. However, it isunderstood that any configuration of the cables 58 a, 58 b and 58 c ispossible. Each of the motors 46 a, 46 b and 46 c operates independentlyto move and level a portion of the upper grilling surface 32 near therespective attachment members 62 a, 62 b and 62 c.

As shown in FIG. 6, operation of a first leveling mechanism 38 a bydriving the motor 46 a (not shown) in a first direction causes the disc52 a to rotate in the direction indicated by arrow A. As a result, thecable 58 a of the first leveling mechanism 38 a lengthens, lowering theupper grilling surface 32 toward the lower grilling surface 30. As shownin FIG. 7, as the motor 46 a (not shown) rotates the disc 52 a in anopposing second direction, indicated by arrow B, the cable 58 a shortensand wraps around the disc 52 a, raising the upper grilling surface 32away from the lower grilling surface 30. Although only operation of thefirst leveling mechanism 38 a is illustrated and described, each of theplurality of leveling mechanisms 38 operates in a similar manner.

In the illustrated, non-limiting embodiment, the lower platen assembly22 is supported by a fixed surface or support structure. In anotherembodiment, illustrated in FIG. 8, the lower platen assembly 22 isconfigured to move respective to the upper grilling surface 32 andincludes at least one leveling mechanism 38 for controlling the tilt,angle, and/or attitude of the grilling surface 30 of the lower platenassembly 22. The leveling mechanisms 38 may include a plurality of motordriven cables 58 similar to the leveling mechanisms shown in FIGS. 3-6,or may include one or more actuators 40 supported by an actuator supportpart 41. The leveling mechanisms 38 are coupled to the control 78 andare configured to operate independently to level a portion of the lowergrilling surface 30.

The grill 20 is automatically calibrated to ensure that the gap 36 ismaintained at the desired size between the lower grilling surface 30 andthe upper grilling surface 32. By calibrated, it is meant that the uppergrilling surface 32 and the lower grilling surface 30 are level to oneanother to ensure proper cooking of the food items 34 in the grill 20.In one example, the grill 20 is calibrated daily to correct anyunleveling of either the upper or lower grilling surface 30, 32 that mayhave occurred during the previous day. However, if an operator noticesthat the upper and lower grilling surfaces 30, 32 are not level duringuse of the grill 20, for example by observing the appearance of the fooditems 34, the operator can initiate the auto-calibration sequence, suchas by pressing a button 84 (FIG. 1) for example.

Referring now to FIG. 9, a method 100 of calibrating a first grillingsurface of a grill 20, such as the upper grilling surface 32 forexample, is illustrated. The method may be applied to either the uppergrilling surface 32 or the lower gritting surface 30. When thecalibration sequence is being performed, the second, opposite grillingsurface, such as the lower grilling surface 30, is generally arranged ina predetermined reference position. In embodiments, where the uppergrilling surface 32 is being calibrated, the lower grilling surface 30may be fixed at the pre-determined position and in embodiments where thelower grilling surface 30 is being calibrated, the lowered position ofthe upper grilling surface 32 may be used as the pre-determinedreference position. In block 102, the calibration sequence is initiatedwhen an operator applies a force to button 84. Upon pressing the button84, in block 104, the control 78 sends a signal to the plurality ofleveling mechanisms 38 a, 38 b, 38 c of the grilling surface beingcalibrated to move the first grilling surface in a first direction,towards the second grilling surface located at the pre-determinedreference position. In block. 106, a sensor 80 detects the current, suchas in the windings of the motors 46 a, 46 b, 46 c, for example, of theplurality of leveling mechanisms 38 a, 38 b, 38 c as the first grillingsurface moves in the first direction. In one embodiment, the sensor 80is a resistor. Although the sensor 80 is described as monitoring thecurrent of the plurality of leveling mechanisms 38 a, 38 b, 38 c, othertypes of sensors 80, such as a linear encoder or hall-effect sensorconfigured to monitor other characteristics of the plurality of levelingmechanisms, for example load or position, are within the scope of theinvention.

When the first grilling surface contacts the second grilling surface,the current of the leveling mechanisms 38 a, 38 b, 38 c change. Forexample, as the upper grilling surface 32 contacts the lower grillingsurface 30, the weight of the upper grilling surface 32 is transferredfrom the cables 58 a, 58 b, 58 c, to the lower grilling surface 30. Byremoving the weight of the upper grilling surface 32 from the cables 58a, 58 b, 58 c, additional power is required to drive the rotation of thediscs 52 a, 52 b, 52 c, and therefore the current in the windings of themotors 46 a, 46 b, 46 c change. Similarly, when the first grillingsurface is separated from the second grilling surface, the current ofthe leveling mechanisms 38 a, 38 b, 38 c change. For instance, when theupper grilling surface 32 is lifted from the lower grilling surface 30,the weight of the upper grilling surface 32 is transferred from thelower grilling surface 30 back to the cables 58 a, 58 b, 58 c. As thecables 58 a, 58 b, 58 c begin to sustain the weight of the uppergrilling surface 32, the tension in the cables 58 a, 58 b, 58 cincreases and therefore the current in the windings of the motors 46 a,46 b, 46 c change.

As the first grilling surface is moved into contact with the secondgrilling surface, the current is detected at each location of the firstgrilling surface. When the sensor 80 detects a change in current, thisindicates that the first grilling surface is in contact with the secondgrilling surface. In block 108, when the percent change in the detectedcurrent increases over a threshold level, the calibration settingsincluding the settings of the plurality of leveling mechanisms 38 a, 38b, 38 c and the recorded location of the first grilling surface arestored in the control 78.

In block 110, the control 78 sends a signal to the plurality of levelingmechanisms 38 a, 38 b, 38 c of the first grilling surface to move thefirst grilling surface in a second direction, away from the secondgrilling surface. As the first grilling surface is moved out of contactwith the second grilling surface, the current is detected at eachlocation of the first grilling surface. When the sensor 80 detects achange in current, this indicates that the first grilling surface iscompletely separated from the second grilling surface. In block 112,when the percent change in the detected current increases over athreshold level, the calibration settings including the settings of theplurality of leveling mechanisms 38 a, 38 b, 38 c and the recordedlocation of the first grilling surface are stored in the control 78. Thetwo locations recorded during each calibration run are generally theboundaries of the level position of the first grilling surface. As shownin block 114, the two locations recorded during each calibration run areinput into an algorithm, stored within the control 78, to generate aresultant calibration setting of the first grilling surface. In oneembodiment, the algorithm is a weighted average of the first locationand the second location.

The calibration steps in blocks 104 through 114 are then repeated. Theplurality of leveling mechanisms 38 a, 38 b, 38 c are operated, such asby driving the motors 46 a, 46 b, 46 c to rotate the respective discs 52a, 52 b, 52 c in the first direction indicated by arrow A for example,to move the first grilling surface into contact with the second grillingsurface. The current of the leveling mechanisms 38 a, 38 b, 38 c isdetected by the sensor 80. When the percent change in the currentincreases over a threshold level, the settings of the levelingmechanisms 38 a, 38 b, 38 c and the location of the first grillingsurface are stored in the control 78. The leveling mechanisms 38 a, 38b, 38 c operate to move the first grilling surface out of contact withthe second grilling surface, such as by rotating the discs 52 a, 52 b,52 c in the second direction indicated by arrow B for example. When thepercent change in the current increases over a threshold level, thesettings of leveling mechanism 38 a, 38 b, 38 c and the location of thefirst grilling surface are stored in the control 78. The locationsrecorded during the learn run are input into an algorithm resulting in acalibration setting.

In block 116, the settings of the leveling mechanisms 38 a, 38 b, 38 cand the calculated locations stored within the control are compared tothe previously stored settings and locations. If the settings andlocations match within a given range, as shown in block 118, thecalibration settings are complete and these values are stored andindicate the calibration settings of the leveling mechanisms 38 a, 38 b,38 c. If the settings of the motor 46 a, 46 b, 46 c and the calculatedlocations of the first grilling surface do not match, the calibrationsteps illustrated in blocks 104-116 are repeated. The calibration stepsare repeated until the settings and the locations match within a givenrange to the settings and locations stored during the previous set ofcalibration steps. By repeating the calibration steps multiple times,more accurate calibration can be ensured. Although the disclosed methodof calibration identifies the calibration settings of the levelingmechanisms 38 a, 38 b, 38 c by detecting a percent change in the currentover a threshold level, it is to be understood that the calibrationsettings can also be determined by detecting a specific current or anaverage current. In addition, although the disclosed method is describedto calibrate the upper and lower grilling surfaces 30, 32, the methodmay be used to determine a distance between a first surface and a secondopposing surface, such as performed during item recognition liarexample.

The calibration steps as described herein are performed using theplurality of leveling mechanisms 38 simultaneously. However, each of theleveling mechanisms 38 may be calibrated individually and sequentially,in any order. In embodiments where each of the plurality of levelingmechanisms 38 is calibrated individually, the calibration settings ofeach leveling mechanism 38 that result in the leveling of the firstgrilling surface are stored in the control 78.

The calibration method described herein provides automated maintenanceof the grill 20 without the use of additional sensors or hardware. Thetwo locations of the first grilling surface, identified when the currentof the leveling mechanisms 38 change, define the boundaries of the levelposition of the first grilling surface. As a result, the calibrationsettings of the plurality of leveling mechanisms are more accurate,leading to improved cooking reliability, consistency, and repeatability.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

The invention claimed is:
 1. A method of calibrating a grill comprising:performing a first calibration run including: monitoring a current of aleveling mechanism as a first grilling surface moves into contact with asecond, opposite grilling surface to determine a first location of thefirst grilling surface; monitoring the current of a leveling mechanismas the first grilling surface moves out of contact with a second,opposite grilling surface to determine a second location of the firstgrilling surface; and storing a first calibration setting including thefirst location and the second location in a control.
 2. The methodaccording to claim 1, wherein the leveling mechanism includes a motorconfigured to move a portion of the first grilling surface.
 3. Themethod according to claim 1, wherein the leveling mechanism is anactuator.
 4. The method according to claim 1, wherein the first grillsurface is an upper grill surface.
 5. The method according to claim 1,wherein the first grill surface is a lower grill surface.
 6. The methodaccording to claim 1, further comprising: comparing the firstcalibration setting with the second calibration setting; and performingan additional calibration run if the second calibration setting is notwithin a given range of the first calibration setting.
 7. The methodaccording to claim 6, wherein the first calibration setting and thesecond calibration setting are used to determine a calibration point ofthe first grilling surface that levels the first grilling surfacerelative to the lower grilling surface.
 8. The method according to claim7, wherein the grill includes a plurality of leveling mechanisms.
 9. Themethod according to claim 8, wherein the calibration point of the firstgrilling surface for each of the plurality of leveling mechanisms isdetermined individually and sequentially.
 10. The method according toclaim 8 wherein the calibration point of the first grilling surface foreach of the plurality of leveling mechanisms is determinedsimultaneously.
 11. The method according to claim 1, further comprising:performing a second calibration run including: monitoring the current ofa leveling mechanism as the first grilling surface moves into contactwith a second, opposite grilling surface to determine a third locationof the first grilling surface; monitoring the current of a levelingmechanism as the first grilling surface moves out of contact with asecond, opposite grilling surface to determine a fourth location of thefirst grilling surface; and storing a second calibration settingincluding the third location and the fourth location in a control. 12.The method according to claim 11, wherein the first location, secondlocation, third location, and fourth location are determined by apercent change in the current over a threshold level.
 13. The methodaccording to claim 11, wherein the first location, second location,third location, and fourth location are determined when the currentreaches a specific value.
 14. The method according to claim 11, whereinthe first location, second location, third location, and fourth locationare determined based on an average current.